Patients with posttraumatic stress disorder (PTSD) demonstrate abnormal psychophysiological responses to stressful events. Given that eye movement desensitization and reprocessing (EMDR) therapy appears to be a treatment of choice for trauma victims, the aim of the present study was to determine if psychophysiological responses to stress decreased after a single EMDR session. Six PTSD patients were treated by an EMDR therapist. Their psychophysiological responses (heart rate and skin conductance) were recorded before and after the EMDR session under two conditions: (a) in a relaxed state and (b) while visualizing their own traumatic event. At the end of the session, all patients had a significant reduction in their PTSD symptoms, which confirms previous results demonstrating the efficacy of the EMDR approach. Second, after only one EMDR session, heart rate and skin conductance during the trauma recall decreased significantly as compared to a relaxing state.